Swish files are a lot smaller that swf files. Why? Swish files are made of instructions like, "Move letter A to the left, and grow it by 8 points." swf files are more like, "Okay, at this frame, the letter A is this big, and at this spot. At the next frame, it's this big, and over here." Get it? Swf files are bigger, becuase they don't read those more generic intructions in the swish files.